A machine gun is a automatic mounted or portable firearm designed to fire rifle cartridges in rapid succession from an ammunition belt or magazine. Not all automatic firearms are machine guns. Submachine guns, assault rifles, battle rifles, pistols or cannons may be capable of automatic fire, but are not designed for sustained fire; as a class of military rapid-fire guns, machine guns are automatic weapons designed to be used as support weapons and used when attached to a mount or fired from the ground on a bipod or tripod. Many machine guns use belt feeding and open bolt operation, features not found on rifles. Unlike semi-automatic firearms, which require one trigger pull per round fired, a machine gun is designed to fire for as long as the trigger is held down. Nowadays the term is restricted to heavy weapons, able to provide continuous or frequent bursts of automatic fire for as long as ammunition lasts. Machine guns are used against personnel and light vehicles, or to provide suppressive fire, either directly or indirectly.

They are mounted on fast attack vehicles such as technicals to provide heavy mobile firepower, armored vehicles such as tanks for engaging targets too small to justify use of the primary weaponry or too fast to engage with it, on aircraft as defensive armament or for strafing ground targets, though on fighter aircraft true machine guns have been supplanted by large-caliber rotary guns. Some machine guns have in practice sustained fire continuously for hours; because they become hot all machine guns fire from an open bolt, to permit air cooling from the breech between bursts. They usually have either a barrel cooling system, slow-heating heavyweight barrel, or removable barrels which allow a hot barrel to be replaced. Although subdivided into "light", "medium", "heavy" or "general-purpose" the lightest machine guns tend to be larger and heavier than standard infantry arms. Medium and heavy machine guns are either mounted on a vehicle. Light machine guns are designed to provide mobile fire support to a squad and are air-cooled weapons fitted with a box magazine or drum and a bipod.

Medium machine guns use full-sized rifle rounds and are designed to be used from fixed positions mounted on a tripod. Heavy machine gun is a term originating in World War I to describe heavyweight medium machine guns and persisted into World War II with Japanese Hotchkiss M1914 clones. A general-purpose machine gun is a lightweight medium machine gun that can either be used with a bipod and drum in the light machine gun role or a tripod and belt feed in the medium machine gun role. Machine guns have simple iron sights, though the use of optics is becoming more common. A common aiming system for direct fire is to alternate solid rounds and tracer ammunition rounds, so shooters can see the trajectory and "walk" the fire into the target, direct the fire of other soldiers. Many heavy machine guns, such as the Browning M2.50 caliber machine gun, are accurate enough to engage targets at great distances. During the Vietnam War, Carlos Hathcock set the record for a long-distance shot at 7,382 ft with a.50 caliber heavy machine gun he had equipped with a telescopic sight.

This led to the introduction of.50 caliber anti-materiel sniper rifles, such as the Barrett M82. Other automatic weapons are subdivided into several categories based on the size of the bullet used, whether the cartridge is fired from a closed bolt or an open bolt, whether the action used is locked or is some form of blowback. Automatic firearms using pistol-calibre ammunition are called machine pistols or submachine guns on the basis of size; the term personal defense weapon is sometimes applied to weapons firing dedicated armor-piercing rounds which would otherwise be regarded as machine pistols or SMGs, but it is not strongly defined and has been used to describe a range of weapons from ordinary SMGs to compact assault rifles. Selective fire rifles firing a full-power rifle cartridge from a closed bolt are called automatic rifles or battle rifles, while rifles that fire an intermediate cartridge are called assault rifles. Assault rifles are a compromise between the size and weight of a pistol-calibre submachine gun and a full-size battle rifle, firing intermediate cartridges and allowing semi-automatic and burst or full-automatic fire options, sometimes with both of the latter present.

Many machine guns are of the locked breech type, follow this cycle: Pulling the bolt assembly/bolt carrier rearward by way of the cocking lever to the point bolt carrier engages a sear and stays at rear position until trigger is activated making bolt carrier move forward Loading fresh round into chamber and locking bolt Firing round by way of a firing pin or striker hitting the primer that ignites the powder when bolt reaches locked position. Unlocking and removing the spent case from the chamber and ejecting it out of the weapon as bolt is moving rearward Loading the next round into the firing chamber. U

West Reading is a locality or informal subdivision of the town of Reading in the English county of Berkshire, with its own railway station which opened in 1906, by which time its main roads were an established housing area. The locality has no formal boundaries, but the name is used to refer to the area to the west of Reading's commercial centre, merging into or to the north of the suburbs of Coley and Southcote, to the east of the suburb of Tilehurst and to the south of the Reading to Bristol railway line; as such it includes the densely populated area along and surrounding the Oxford Road as far as the foot of Norcot Hill, a typical example of the British town's rows of terraced houses, as well as the more affluent area between this road and the Bath Road and alongside Tilehurst Road as far as Prospect Park and its slopes. West Reading is in the borough of Reading, comprising Battle ward together with parts of Abbey, Minster and Southcote wards. Whereas most of this area is in the Reading West parliamentary constituency, the Abbey ward portion is in the Reading East parliamentary constituency.

The area has a 21st-century supermarket and residential estate on the site of Battle Hospital, once Reading's largest general hospital in site area, adjoining Oxford Road. The Elm Park stadium in West Reading was home to Reading Football Club from 1896 to 1998 and was redeveloped as a housing estate between 1998 and 2000; the Bath Road Reservoir, a minor water storage reservoir and ornate brick-built pumping station is an elevated landmark along the Bath Road, built in the late Victorian era. The early 21st-century years saw residents' opposition defeat an attempt by Thames Water to demolish the pumping station, level the reservoir and redevelop the site for housing. West Reading is served by Reading West railway station on the local lines between Reading/Basingstoke and Reading/Newbury. Reading Buses operates frequent services along the Oxford Road, Bath Road and Tilehurst Road corridors; the district contains the Church of England parish churches of All Saints, Holy Trinity, St. Mark and Tylehurst St George, together with English Martyrs Church in the Catholic church.